OK Thomas, now you have me confused. It sounds like you are recommending this sequence:

Paper uncovered
1st exposure = 32 seconds
Cover a bit of paper and give 22 seconds more (that strip would now have a total of 54 seconds).
Cover a bit of paper and give 16 seconds more (that strip would now have a total of 70 seconds).
Cover a bit of paper and give 11 seconds more (that strip would now have a total of 81 seconds).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 89 seconds).
Cover a bit of paper and give 5.6 seconds more (that strip would now have a total of 94.6 seconds).
Cover a bit of paper and give 4 seconds more (that strip would now have a total of 98.6 seconds).

Those are huge times! Or do you mean:

Paper uncovered
Expose for 4 seconds
Cover a bit of paper and give 5.6 seconds more (that strip would now have a total of 9.6 seconds).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 17.6 seconds).
Cover a bit of paper and give 11 seconds more (that strip would now have a total of 28.6 seconds).
Cover a bit of paper and give 16 seconds more (that strip would now have a total of 44.6 seconds).
Cover a bit of paper and give 22 seconds more (that strip would now have a total of 64.6 seconds).
Cover a bit of paper and give 32 seconds more (that strip would now have a total of 96.6 seconds).

Either way it makes no sense to me. What am I missing?

In a previous thread I recommended:

Paper uncovered
Give an exposure of 8 seconds
Cover a bit of paper and give 2 seconds more (that strip would now have a total of 10 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 2.5 seconds more (that strip would now have a total of 12.5 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 3.5 seconds more (that strip would now have a total of 16 seconds which is one-third stop more than the previous strip has and one full stop more than the first strip).
Cover a bit of paper and give 4 seconds more (that strip would now have a total of 20 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 5 seconds more (that strip would now have a total of 25 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 7 seconds more (that strip would now have a total of 32 seconds which is one-third stop more than the previous strip has and two full stops more than the first strip).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 40 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 10 seconds more (that strip would now have a total of 50 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 14 seconds more (that strip would now have a total of 64 seconds which is one-third stop more than the previous strip has and three full stops more than the first strip).

This sequence above increases in 1/3-stop geometric intervals and each strip is very distinct and appears visually to be the same amount of increase between each step. Conversely, an arithmetic sequence with an interval of 5-seconds becomes less and less effective as the total time increases. From 5 seconds to 10 seconds, the 5-second interval represents 100% change in exposure (or one full f/stop) but from 45 seconds to 50 seconds is only about a 10% increase.

Just write the test strip exposure sequence down and keep it next to your enlarger. That way you won't have to memorize the sequence and you will have much improved test strips.

Joe

.

Originally Posted by Thomas Bertilsson

Make sure that the material you use to cover your paper with when making the test strip is entirely opaque. Or some light will shine through and fog the paper underneath.

Also, instead of doing 5 second increments, I recommend using the values on the f/stop ring on your camera lens. 32s, 22s, 16s, 11s, 8s, 5.6s, and 4s. You go backwards like that, so that the first strip is 32 seconds, next is 22 seconds, etc. It gives you one full stop between strips and gives you a better idea of what different levels of exposure will do in your final print.

Good luck. Keep posting back here with your results.

Last edited by smieglitz; 05-20-2013 at 02:27 PM. Click to view previous post history.

Try what R Gould has suggested then there is no confusion on times for each section. Unless confusion has crept in I can see no other way in which you can have the problem you describe, given that you are sure that all other things are identical between the test strip and full print.

Try what R Gould has suggested then there is no confusion on times for each section. Unless confusion has crept in I can see no other way in which you can have the problem you describe, given that you are sure that all other things are identical between the test strip and full print.

pentaxuser

With some beginning printers the constant test strip interval method does produce confusion because the strips becomes harder to discern at longer exposures, and sometimes the first exposure doesn't show with an arithmetic test strip (e.g., 5+5+5+5...). At least that has been my experience working with introductory-level students in a community college darkroom. It is also very common for them to confuse the darkest strip with the least exposure and vice versa.

Starting at 32 seconds, and counting backwards you expose one strip of the sheet.
Then at 22 seconds you move the light blocking device again to expose the next strip of the paper.
Repeat at 16, 11, 8, 5.6 seconds, and at 4 seconds the whole sheet should be illuminated, and at 0 seconds turn enlarger light off.

I don't know how much simpler it can get? What's the source of confusion?

- Thomas

Originally Posted by smieglitz

OK Thomas, now you have me confused. It sounds like you are recommending this sequence:

Paper uncovered
1st exposure = 32 seconds
Cover a bit of paper and give 22 seconds more (that strip would now have a total of 54 seconds).
Cover a bit of paper and give 16 seconds more (that strip would now have a total of 70 seconds).
Cover a bit of paper and give 11 seconds more (that strip would now have a total of 81 seconds).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 89 seconds).
Cover a bit of paper and give 5.6 seconds more (that strip would now have a total of 94.6 seconds).
Cover a bit of paper and give 4 seconds more (that strip would now have a total of 98.6 seconds).

Those are huge times! Or do you mean:

Paper uncovered
Expose for 4 seconds
Cover a bit of paper and give 5.6 seconds more (that strip would now have a total of 9.6 seconds).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 17.6 seconds).
Cover a bit of paper and give 11 seconds more (that strip would now have a total of 28.6 seconds).
Cover a bit of paper and give 16 seconds more (that strip would now have a total of 44.6 seconds).
Cover a bit of paper and give 22 seconds more (that strip would now have a total of 64.6 seconds).
Cover a bit of paper and give 32 seconds more (that strip would now have a total of 96.6 seconds).

Either way it makes no sense to me. What am I missing?

In a previous thread I recommended:

Paper uncovered
Give an exposure of 8 seconds
Cover a bit of paper and give 2 seconds more (that strip would now have a total of 10 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 2.5 seconds more (that strip would now have a total of 12.5 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 3.5 seconds more (that strip would now have a total of 16 seconds which is one-third stop more than the previous strip has and one full stop more than the first strip).
Cover a bit of paper and give 4 seconds more (that strip would now have a total of 20 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 5 seconds more (that strip would now have a total of 25 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 7 seconds more (that strip would now have a total of 32 seconds which is one-third stop more than the previous strip has and two full stops more than the first strip).
Cover a bit of paper and give 8 seconds more (that strip would now have a total of 40 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 10 seconds more (that strip would now have a total of 50 seconds which is one-third stop more than the previous strip has).
Cover a bit of paper and give 14 seconds more (that strip would now have a total of 64 seconds which is one-third stop more than the previous strip has and three full stops more than the first strip).

This sequence above increases in 1/3-stop geometric intervals and each strip is very distinct and appears visually to be the same amount of increase between each step. Conversely, an arithmetic sequence with an interval of 5-seconds becomes less and less effective as the total time increases. From 5 seconds to 10 seconds, the 5-second interval represents 100% change in exposure (or one full f/stop) but from 45 seconds to 50 seconds is only about a 10% increase.

desertratt, I'm not here to argue with anyone. I'm just trying to understand what Thomas is talking about and help someone who is confused over the method they are using. You're right. This ain't the Manhattan Project, but the geometric test strip isn't rocket surgery. Just write it down and try it.

I used to hate asparagus when I was a little kid because of how it was served up (canned, boiled, overcooked, and mushy). Once I tried it a different way (fresh and steamed), it became one of my favorite things.

Starting at 32 seconds, and counting backwards you expose one strip of the sheet.
Then at 22 seconds you move the light blocking device again to expose the next strip of the paper.
Repeat at 16, 11, 8, 5.6 seconds, and at 4 seconds the whole sheet should be illuminated, and at 0 seconds turn enlarger light off.

I don't know how much simpler it can get? What's the source of confusion?

- Thomas

Aha! Now I know what you are doing. You are counting backwards from the total exposure time and uncovering the paper at certain points. I thought we were talking about progressively covering the previously exposed strip, not uncovering unexposed paper.

If you do your full print by resetting the timer for the full time, it's possible your timer isn't consistent. Depending on what type of timer you use (and I've tested mine and am fairly sure I can get away with adding up the shorter times), if you do a test strip with multiple hits of 5 seconds each, then you should use the number of hits with the timer still set at 5 seconds - not resetting the timer for 10 seconds.
I know Thomas' method sounds tougher to imagine, but many people swear by it (and it does make sense after using it). I do my test strips the way you explained you were, btw, and I don't use Thomas's method (though I've considered switching).

After giving it some thought, Thomas' method is probably the easiest way to do a geometric series (if you can remember the standard f/stops on your lenses). His method has a bit coarser interval than mine, but we are basically doing the same thing and probably would be very close on a printing time. Mechanically, Thomas' way is simpler because he is giving really only one continuous exposure and doesn't have to reset the timer. This also eliminates any intermittency effect, or as Beth has noted, cumulative timer error which could be happening with the method I suggested.

Are you sure? When you do the last 5 second exposure is the entire sheet of paper uncovered? Examine the print you made after the test strip/print carefully. You said it was too light. Does it look like the "5 second" strip on the test print?

Diagnose the problem first. I don't think there is a need to change the test print method you are using. It is fine. Just make sure you are doing it properly.